Funds are requested to support the Gordon Conference on Cell Contact and Adhesion. This conference first met in 1973. It has convened every other year since that time. Altogether, there have been 9 sessions. Each session has been highly oversubscribed. Thus, there has been a sustained interest over the past 18 years in this general area of science. The 1991 Conference has been organized to avoid, as much as possible, overlap in topics and speakers with other related conferences. The topics to be covered are of interest to a diverse community of scientists including molecular biologists, cell biologists, developmental biologists, neurobiologists, oncologists, hematologists etc. The topics will examine the molecular mechanisms controlling cell interactions in several interesting biological systems. They will include discussions of specific cell surface receptors such as those of the integrin family, the immunoglobulin superfamily, the cadherins, the Selectin family etc. Topics of cell motility, cytoskeleton/membrane interactions and the mechanisms of neurite extension and nerve formation will be discussed. Several speakers will discuss the role of the extracellular matrix in developmental processes as well as in cell division, migration and differentiation. Finally, receptor function in endothelial cell/leukocyte interactions as well as receptors in the immune system will be considered with special emphasis on the modulating influence of receptor modifications such as phosphorylation or alternative splicing on receptor organization and function. Thus, the topics will be interest to a variety of scientists whose common interest is the molecular basis of cell adhesive mechanisms.